This invention relates to ink jets capable of ejecting droplets of ink.
An ink jet capable of ejecting a droplet of ink on demand is disclosed in copending application Ser. No. 336,603, filed Jan. 4, 1982 which is assigned to the assignee of this invention. The ink jet disclosed therein is capable of operating in a fill before fire mode, i.e., the chamber is expanded by energizing the transducer during filling of the chamber and the chamber contracts upon de-energization of the transducer at which time a droplet of ink is ejected. Such a fill before fire mode is to be contrasted with the more usual case of expanding the chamber during a state of de-energization of the transducer at which time filling occurs and contracting the chamber upon energization of the transducer at which time a droplet of ink is ejected.
In an ink jet which operates in a fill before fire mode, it is necessary that the deformable chamber wall follow the transducer motion such that the chamber can expand as the transducer contracts so as to permit filling of the chamber. The appropriate coupling between the deformable wall such as a diaphragm and the transducer may be achieved by mechanical fastening means such as a rivet or other means for attachment. However, such a mechanical fastening means may present reliability problems. Moreover, such mechanical fastening means may present difficult assembly problems where it will be appreciated that the dimensions of an ink jet are extremely small. Furthermore, mechanical fastening means may make it difficult to achieve the necessary precision so as to permit reproducability in ink jets, i.e., each ink jet in an array is identical to every other ink jet in the array to assure high quality printing from an array of ink jets. It is also important that the coupling between the transducer and the deformable wall or diaphragm not degrade over time, be stable with respect to temperature, low cost and resistant to any leakage of ink. It is further desirable that the fastening means be relatively low cost.